Elastic yarn and method of making the same



Patented Dec. 1 5, 1 936 PATENT OFFICE ELASTIC Y ARN AND METHOD OF MAKING THE SAIWE Fayette D. Chittenden, Providence, R. I., assignor to United States Rubber Products, Inc., New York, N. Y., a corporation of Delaware No Drawing. Application June 14, 1935, Serial No. 26,617

3 Claims. (Cl. 117-21) This invention relates to elastic yarn consisting of an elastic core having oppositely wound coverings thereupon, and to a method of making the same.

Elastic yarn such as herein contemplated is extensively used in the manufacture of elastic knitted and woven goods employed in the construction of corsets, girdles and other garments. It is also used for other purposes and is or may be of a size and character to enable it to be knitted in a fine gauge knitting machine, and woven as weft.

Such an elastic yarn in order to meet satisfactorily the requirements of its manufacturers and the trade must fulfill a number of exacting conditions.

One such requirement is that it shall run well on the core covering machine without excessive breakage of covering yarns.

. A second requirement is that when this elastic yarn is stretched to near the breaking point, each cover, as well as the core shall take its share of the pull and all three shall break approximately together, or the covers shall break before the core. This property is commonly known as the break.

A third requirement is that the elastic yarn shall be flexible for knitting purposes, and shall have a soft hand or feel caused by forming theouter covering of a yarnhavingvery little twist when in the core-covering position.

A fourth requirement is that the elastic yarn shall be well balanced so that it will not curl or kink when in the skein or other relaxed condition and shall accommodate the contraction and expansion of the elastic core.

Heretofore, large quantities of elastic yarn having all of these requirements and fine enough to be knit in a fine gauge knitting machine, have been produced by employing either plied yarns or multiple ends of singles yarns for both the inner and outer covering, butso far as applicant is aware, no practical method was known prior to the present invention, for producing a satisfactory fine elastic yarn having a single end inner singles spun yarn the wrapping operation which removed twist has reduced the yarn to the form of roving and breakage has been so excessive that the preparation of this type of elastic'yarn was impractical. With plied yarns and multiple ends of singles yarns this difficulty does not arise because when' twist is removed from the singles yarns either the ply twist is increased proportionately or the multiple ends are twisted together proportionately so that excess breakage does not occur.

It is found in practice that when an elastic yarn is formed by wrapping spun yarns in opposite directions about an elastic core to provide an inner and outer covering thereupon, the best results as to strength, break and hand are obtained when the inner wrapping as it lies on the core is in a high degree of twist and the outer wrapping as it lies on the core is in a low degree of twist.

Because of the above mentioned difficulty, all attempts heretofore to prepare in a practical man ner satisfactory elastic yarn of the finer sizes having a single end of singles yarn for its inner cover and a single end of singles yarn for its outer cover, have failed, so far as applicant is aware. These difliculties, however, are somewhat less serious in covering the larger elastic cores with proportionately larger yarns, because a relativey arge single end yarn having a low twist can be handled and worked better than a very fine single end yarn having a low twist.

Having in mind the foregoing, the present invention resides in an elastic yarn formed of an elastic core having an inner covering of a single and of singles spun yarn wound upon the core in one direction and an outer covering of a single end of singlesspun yarn wound upon the core in the opposite direction so as to impart to the covered yarn the desired hand, break and other requirements. The invention also resides in the method of making this yarn.

The elastic yarn of the present invention is produced by employing a filling or low twist yarn for the inner cover and a warp or high twist yarn for the outer cover, the direction of twist being the same in both yarns, and by so applying the filling twist yarn that its twist is greatly increased by the winding mechanism that wraps it about the core, and by so applying the warp twist yarn that covering operation. To illustrate, if cotton yarn than 4.00 be used and that for the outer core cover employed is of very fine size Since the twist of the filling twist yarn for the inner cover is increased during the core-covering operation, its strength is increased during the winding operation but the twist is not increased to the point where the yarn becomes brittle or tends to kink or loop during wrapping. The warp twist yarns for the outer cover, due to its high twist, will work well in the winding machine, but since the windingoperation is'in a direction to remove most of this twist it will impart to the finished elastic yarn flexibility, a soft hand, and a good break.

To illustrate, let it be assumed that an elastic.

ployed, the direction of twist being the same for, both yarns. Then, after the yarn for the inner cover is applied to the core, it will have a twist multiplier of about 7 or 8 and after the yarn for the outer cover is applied to the core it will have a twist multiplier of about 1.50. In other words,

the twist of the inner cover yarn would be greatly increased while the twist of the outer cover yarn would be greatly reduced. The term twist multiplier is a constant used in the spinning of textile yarns.

The advantages of the present method of covering an elastic core over the methods used heretofore are at once-apparent since through the present method a large saving in cost ofcovering yarn is secured, since a covering of singles yarn is obviously less expensive than plied yarns or mutiple ends of singles yarn of corresponding size and strength.

As above pointed out, the, practice heretofore was to employ either one end of a ply yarn or multiple ends of singles yarn for both the inner cover and'outer cover, thus necessitating the use of at least four ends of yarn in the two covers. Through the present invention. a single end of singles yarn is employed for the inner cover and for the outer cover, with the result that-only two ends of yarn are required to completely cover the elastic core. Each single end yarn employed in accordance with the present invention to form a cover may be larger than the individual singles yarns forming the ply yarn or multiple ends of singles yarns used heretofore as a cover. In other words, two ends of heavier yarns are now substituted for four or more ends of finer and more expensive yarn previously used.

It is found in practice when-employing a single end of singles yarn of spun fibers for each cover for the elastic core that the spindle that removes twist from the yarn during the core-covering operation should carry a higher twist yarn than a spindle that is inserting twist during the coreof the type commonly employed for single end covering in carrying out the present invention is.

used, it is highly desirable that for the inner core cover a yarn spun with a twist multiplier less a yarn spun with a twist multiplier greater than 4.00 be used.

In order that a fuller understanding of the invention may be had, the following examples are given, wherein T. M. stands 'for twist multiplier, C P. stands for combed peeler and Sak. for sakellaridis. In each of these examples the core was covered while in a stretched condition.

Inner cover-1 end 50/1 C. P.cotton3.50

Outer cover1 end 50/1 C. P. cotton5.00

, T. M. i y 3. Elastic core100s rubber thread.

Inner cover-1 end 50/1 C. P. cotton-3.50

T. M. Outer cover-1 end 36/1 C. P; cotton4.50

T. M. 4. Elastic core-125s rubber thread.

-- Inner cover1 end 120/1 spun silkturns per inch 1.40 T. M. 4 I Outer cover--1 end 120/1 spun silk35 turns per inch 3.20 T. M. 5. Elasticcore100s rubber thread.

Inner cover1 end 36/1 C. P. cotton-3.00

Outer cover1 end 50/1 C. P.- cotton-5.00

' T. M. 6. Elastic core-125's rubber'thread. v

Inner cover-1 end 80/1 Sak. cotton-3.50

T. M- I V Outer cover1 end 80/1 Sak. cotton-5.00

T. M. In each of the examples above given the yarn for both the inner and outer cover was right twist, that is, was regular twist. yarn as defined by the A. S. T. M. (American Society of Testing Materials) specifications, and in each of these examples the spindle applying the inner cover will at all times have sufiicient twist to prevent.

excessive breakage in the covering operation.

In practice, it is found desirable to maintain the rubber core under considerable tension while the coverings are being wrapped thereupon, but the coverings may be so applied that they will hold the core stretched anywhere from a slight to a considerable degree,

The above examples are merely illustrative of the invention and are not to be regarded as limiting the same beyond the extent required by the enough to knit in a fine gauge knitting machine which comprises tensioning an elastic core, forming an inner cover upon the core by revolving about the core a supply of single end of singles low twist yarn so as to greatly increase its twist and strength during the winding operation and upon the core, forming an outer cover over said inner coverby revolving in the opposite direction about the corea supply of single end singles high twist yarn to thereby untwist the 'yam until it approaches a rovinglike condition and spirally winding it over the inner cover to form a soft outer cover, the twist or both yarns being in the same direction. Y

2. The method of making elastic yarn fine I enough to knit in afine gauge knitting machine,

which comprises tensioning an elastic core, forniing an inner helical cover upon the core by revolving about the core a supply of single end of singles low twist yarn so as to increase its twist during the covering operation and upon the core, forming an outer cover over said inner cover by revolving in the opposite direction about the core a supply of single end singles high twist yarn to thereby reduce its twist during the covering operation and winding it over the inner cover to form a helical outer cover, the twists of both yarns being in the same direction.

3.'The method of making elastic yarn fine enough to knit in a fine gauge knitting machine,

which comprises tensioning an elastic core, forming an inner helical cover upon the tensioned core by revolving about the core in a direction to increase its twist during the covering operation a supply 0! single end of singles cotton yarn spun with a twist multiplier of not more than 4, forming an outer cover over said inner cover by revolving in the opposite direction about the core so as to reduce its twist during the covering operation a supply of single end singles cotton yarn spun with a twist multiplier of more than 4 and helicaliy wind this yarn over the inner cover, the twist of both yarns being in the same direction.

FAYETTE D. CHI'I'I'ENDEN. 

